The other option is a helmet with it built in.... Viper RS V121. Apparently, the latest model now allows helmet to helmet comms as well as hooking up with other bluetooth devices, i.e. mp3... mobile... gps voice directions.. etc. Previous model Viper RS V101 does not do helmet to helmet.
Charge from flat takes 4 hours... 2 hours talk time.. 100 hours standby.
It has an internal sun visor, operation is independent from the main visor. Appears to be reasonable quality and the price is comparable with a helmet of similar cost.
Personally , I don't have experience of this helmet but I am considering one or two for myself. They're selling in our shops for GBP £120.. I'd imagine that you may sell for US $100 - $150... maybe a discount if more than one.
I've heard reports that the bluetooth quality in the Viper RS V121 might not be good enough for music and although its supposed to have wind noise canceling technology it may not work well enough above 50mph. But then again you get helmet and bluetooth for basically half of what both would cost separately.
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Other systems :
http://www.starcom1.com - may not be available in USA, however this system has up to 150 metre range, ideal for bike to bike. It may be that the range is what deems it not for sale in USA, not sure.
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When buying bluetooth devices always check its "Bluetooth Class" this will give you an idea of what to expect distance wise....
Bluetooth Classes and distances:
Class 1 100mW (20dBm) 100 meters
Class 2 2.5mW (4dBm) 10 meters
Class 3 1mW (0dBm) 1 meter
So, if you just want rider <-> pillion.. class 2 will do the job. On the other hand bike <-> bike then class 1.
However, Bluetooth generally can only communicate with one other device at a time, so conferencing is not an option with bluetooth. So if bike <-> many bikes then FM transceivers is the way to go and the price starts creeping up as well.
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Cost, fit for purpose, and quality for the job all need to be considered.